Lighting device with central and peripheral illumination

ABSTRACT

A light assembly includes a light source and a reflector having a reflective interior surface and a central opening. A toroidal-shaped toroid optic includes a central bore and the light source is positioned in the central bore. The toroid optic is positioned within the central opening of the reflector. A broadening lens is attached to the reflector and positioned adjacent to the toroid optic. The broadening lens includes a central optic.

CLAIM OF PRIORITY

This application claims priority to U.S. Provisional Patent ApplicationNo. 62/057,622, filed Sep. 30, 2014, the contents of which are herebyincorporated by reference.

FIELD OF THE INVENTION

The present invention relates generally to flashlights and, inparticular, to a lighting device having central and peripheralillumination.

BACKGROUND

Lighting devices, such as flashlights and cap lamps in general aretypically designed to have either a bright center spot for centralillumination or a dispersed type flood light for peripheralillumination. Alternative prior art lighting device designs have theability to be adjustable to obtain varying degrees of spot/flood light.In some cases a light may have multiple LED's with one main light facingforward to give the spot light and one facing down (90 degrees from themain light) to illuminate and act more like a flood light.

Slips, trips and falls account for a large portion of accidents and lostwork time. A significant contributor to these types of accidents is thelack of good lighting. An individual's ability to recognize objects andmaintain good spatial orientation is directly affected by the light thatis available to the individual. Both good central and peripheral lightare needed to have the best visual acuity and spatial orientation. Whenan individual does not have good object recognition (visual acuity)and/or good spatial orientation, the potential for a slip, trip or fallby the individual is significantly increased. One's sense of balance issignificantly affected by light levels. In poor lighting levels,tripping on an object is more likely to result in a fall and injury. Ingood lighting, where there is good spatial orientation, an individual ismore likely to recover from bumping into an object resulting in astumble rather than a fall.

To obtain a higher level of safety, there is a need for a light thatproduces both a bright center spot light and a good peripheral light(flood light). A light that provides both a bright center spot andbright peripheral light results in a safer light. The ability for alight to maintain a bright center spot while simultaneously lighting theperipheral region of a user's sight to provide a wide field of view istherefore desirable.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a prior art light assembly including alight emitting diode (LED) assembly connected to a reflector;

FIG. 2 is a side elevational view of the prior art light assembly ofFIG. 1 illustrating the distribution paths taken by light produced bythe LED assembly;

FIG. 3 is a side elevational view of a light assembly provided with alight tube having an axicon in accordance with a first embodiment of thepresent invention illustrating the distribution paths taken by lightproduced by the LED assembly;

FIG. 4 is an enlarged view of the LED assembly and the light tube havingan axicon of FIG. 4 illustrating the distribution paths taken by lightproduced by the LED assembly;

FIG. 5 is a side elevational view of the light tube having an axicon ofFIGS. 3 and 4;

FIG. 6 is an enlarged view of the portion of the axicon indicated bycircle A in FIG. 5;

FIG. 7 is a perspective view of the light pipe with axicon of FIGS. 3-6;

FIG. 8 is a perspective view of lens including the light pipe withaxicon of FIGS. 3-7;

FIG. 9 is a front elevational view of the lens of FIG. 8;

FIG. 10 is a side elevational view of the lens of FIGS. 8 and 9;

FIG. 11 is a cross sectional view of the lens of FIGS. 8-10 taken alongline A-A of FIG. 10;

FIG. 12 is an exploded perspective view of a flashlight thatincorporates the lens of FIGS. 8-11;

FIG. 13 is a sectional perspective view of a light assembly providedwith a toroid optic, a mirror reflector, a broadening optic and a frontwindow in accordance with a second embodiment of the present invention;

FIG. 14 is a side elevational view of the light assembly of FIG. 13illustrating the distribution paths taken by light produced by the LEDassembly;

FIG. 15 is a perspective view of the toroid optic of the light assemblyof FIGS. 13 and 14;

FIG. 16 is a cross sectional view of the toroid optic of FIG. 15;

FIG. 17 is a perspective view of the broadening optic and front windowof the light assembly of FIGS. 13 and 14;

FIGS. 18A and 18B are cross sectional views of the broadening optic andfront window of FIG. 17;

FIG. 19 is a perspective view of the mirror reflector of the lightassembly of FIGS. 13 and 14;

FIG. 20 is a cross sectional view of the mirror reflector of FIG. 19;

FIG. 21 is a schematic showing an example of the illumination areaprovided by a flashlight using the light assembly of FIGS. 13 and 14;

FIGS. 22a and 22b are side elevational views of a light assembly and alight assembly including a reflector provided with a light tube having atextured proximal surface;

FIG. 23 is a side elevational view of a light assembly with a convexlens on the proximal surface and a textured surface on the distal end ofthe light tube;

FIG. 24 is a front elevational view of a lens assembly in a cap lampembodiment of the invention;

FIG. 25 is a cross sectional view of the lens assembly of FIG. 24 takenalong lines 25-25;

FIG. 26 is a side elevational view of a reflector in the cap lampembodiment;

FIG. 27 is a cross sectional view of the reflector of FIG. 26 takenalong line 27-27;

FIG. 28 is a perspective view of a toroid optic of the cap lampembodiment with interior detail shown in phantom;

FIG. 29 is an exploded view of an assembly that includes the toroidoptic of FIG. 28, the reflector of FIG. 27 and a circuit board to whicha light source is mounted;

FIG. 30 is an exploded perspective view of the cap lamp embodiment ofthe invention.

DETAILED DESCRIPTION OF EMBODIMENTS

A prior art light assembly is indicated in general at 30 in FIGS. 1 and2 and is of the type that is typically installed in flashlights andreceives electrical power from battery cells or a battery power pack. Asillustrated in FIGS. 1 and 2, a light emitting diode (LED) assemblyincluding an LED 32 and an associated circuit board 34 is attached to areflector 36 so that the LED 32 is positioned within a central openingof the reflector. While embodiments of the invention are described belowin terms of an LED light source, alternative types of light sourcesknown in the prior art could be used instead.

In operation, the light rays produced by the LED 32 follow the pathsillustrated in FIG. 2. More specifically, direct light rays, such asindicated at 42 a and 42 b, emit out of the front of a flashlight withinwhich the light assembly 30 is installed while reflected light rays,circled at 44 in FIG. 2, bounce off of, or are reflected by, reflector36 prior to emission out of the front of the flashlight. The reflectedlight rays 44, which are directed to form a bright central or centerspot light, typically contribute greater than 99% of the peak lightintensity produced by the flashlight. The direct light rays exiting thelight assembly at a diverging angle, such as 42 b in FIG. 2, providepoor or virtually no light in the peripheral region of the front of theflashlight.

A light assembly, indicated in general at 50 in FIG. 3, features a lightemitting diode (LED) assembly including an LED 52 and an associatedcircuit board 54. The light assembly is attached to a reflector 56 sothat the LED 52 is positioned within a central opening of the reflectorand surrounded by the shiny or reflective internal surface of thereflector. In accordance with a first embodiment, a clear, solid,cylindrical light pipe 60 features an axicon (62 in FIGS. 4-7) and ispositioned at the entrance of the light pipe (i.e. the end facing theLED 52). As will be explained below, the light pipe may be formed with,and/or held in place by, the lens of a flashlight within which the lightassembly 50 is installed. As an example only, the light tube 60 may beconstructed from solid high clarity polycarbonate, acrylic or anotherplastic.

As illustrated in FIG. 3, a portion of the light produced by the LED 52(see 65 in FIG. 4) is reflected off of the reflector 56 to provide lightrays 64 which enables the flashlight to provide a bright central spot orspot light. The remaining light rays 66 (FIGS. 3 and 4) enter theproximal end of the light pipe 60, and thus the axicon 62.

As illustrated at 72 in FIG. 4, the angular distribution of the lightrays entering the light pipe is controlled by the shape of the axicon sothat the light rays are reflected within the light pipe as they traveltoward the light pipe distal end.

The shape of the axicon, the dimensions of the light pipe (i.e. lengthand diameter) and the distance of the light pipe proximal end from theLED is selected such that the light rays exiting the distal end of thelight pipe are directed towards the peripheral area of the front of theflashlight as illustrated at 74 in FIGS. 3 and 4. These light rays 74provide bright peripheral illumination for the flashlight.

Examples of dimensions for the light pipe 60 and axicon 62 for an LEDhaving an output normalized to 100 lumens are provided with reference toFIGS. 5-7. More specifically, the length of the light pipe 60, indicatedby arrows 76 of FIG. 5, may be approximately 24.65 mm, while thediameter of the light pipe, indicated by arrows 78 in FIG. 5, may beapproximately 9 mm. The circular flat central region of the axicon mayhave a diameter, indicated by arrows 82 in FIG. 6, of approximately 0.52mm.

As an example only, the three-dimensional profile for the axicon 62,using a standard x, y, z coordinate system (see FIGS. 5 and 7), may bedefined using the following equation and tables:

y=A+Bx+Cx ² +Dx ³ +Ex ⁴ +Fx ⁵ +Gx ⁶

A 4.495 B −3.600E−01 C −3.565E−01 D  2.899E−01 E −1.367E−01 F  3.006E−02G −2.525E−03

Z y (Radius) 0.000 4.500 0.159 4.426 0.318 4.347 0.477 4.264 0.636 4.1780.794 4.087 0.953 3.992 1.112 3.894 1.271 3.792 1.430 3.686 1.589 3.5771.748 3.464 1.907 3.347 2.065 3.226 2.224 3.102 2.383 2.973 2.542 2.8402.701 2.703 2.860 2.560 3.019 2.413 3.178 2.260 3.336 2.100 3.455 1.9333.654 1.758 3.813 1.573 3.972 1.375 4.131 1.161 4.290 0.924 4.449 0.6464.607 0.262 4.607 0.000

Of course alternative profiles and sizes may be used for the axicon 62.

As shown in FIGS. 8-11, the light pipe 62 may be integrally formed witha lens 82 so that the distal end of the light pipe, shown at 83 in FIGS.5 and 7, is joined to the lens. For example, the lens and light pipe maybe molded from clear plastic as a single part. In an alternativeembodiment, the distal end 83 of the light pipe 60 could be joined byadhesive, or otherwise secured, to the lens 82.

The lens 82 of FIGS. 8-11 also features legs 84 having tabs 86 so thatit may be assembled within a flashlight as illustrated in FIG. 12. Morespecifically, with reference to FIG. 12, a flashlight has a tube-shapedbody 90 having a head open end 92 and a tail open end 94. Duringmanufacture, a switch housing 96 and switch assembly 98 are insertedinto the body of the flashlight and aligned with a switch opening 102. Aswitch 104 is secured within the switch opening and engages the switchassembly so that the switch may be used to turn the flashlight on andoff. An LED assembly 106 is also placed in the flashlight body adjacentand operatively connected to the switch assembly 98 and is held in placeby screws 108. As described previously, the LED assembly includes an LEDthat is positioned within the central opening of a reflector 56. Thereflector is also received within the body of the flashlight as is anO-ring 110. The lens 82, including light pipe 60 is then inserted intothe open end 92 of the body and locked in place with the tabs and legs84. Battery cells are inserted through the tail end opening 94 of thebody and are held in place by a tail spring 112 and tail cap 114, wherethe tail cap is threaded to engage the tail end of the body. A tailO-ring 116 is provided between the tail cap and the tail end of the body92.

In alternative embodiments of the invention, the light pipe may bemounted within the body 90 of the flashlight separate from andindependently of the lens 82. For example, the light pipe could bemounted within the body by a mounting bracket, plate or disk, aformation molded into the body or any other mounting method available inthe art.

Furthermore, alternative embodiments of the light pipe may include atextured proximal surface, as indicated at 160 in FIGS. 22a and 22b ,instead of an axicon. In another alternative embodiment, the light pipemay be provided with a convex lens surface on the proximal end,illustrated at 170 in FIG. 23, with a textured diffuser surface 172positioned on the distal end.

In an alternative embodiment a light assembly, indicated in general at150 in FIGS. 13 and 14, includes a reflector 152 having an internalmirror surface 154, or other internal reflective surface, and anenlarged central opening 156 (also shown in FIGS. 19 and 20). Positionedwithin the central opening 156 of the reflector is a toroidal ordoughnut-shaped toroid optic 158 formed of a material such as clearpolycarbonate or acrylic. Alternative clear materials may be used.

As shown in FIGS. 13-16, the toroid optic 158 includes a truncatedcone-shaped central bore 162 with side walls 163 that taper outward froma proximal end towards a distal end. An LED 164 is positioned within theproximal end of the central bore 162. As best shown in FIG. 16, thetoroid optic 158 features a generally triangular cross section 166having a curved outer surface 172.

A broadening lens or cover 174 is positioned on the annular distal edgeof the reflector and is preferably formed from clear polycarbonate oracrylic (but other materials may be used). The broadening lens has anannular flat window portion 176 surrounding a near beam center-fill lens178 and a dome lens 182. The broadening lens also has a front window180. The dome lens 182 is positioned in the middle of the near beamcenter-fill lens 178. The functionality of each of these components willbe explained below. The components may be integrally formed of clearmaterial, or may be formed separately and joined together.

In operation, with reference to FIG. 14, light rays produced by the LED164 are directed by the toroid optic to provide both a center beam forcentral illumination and a wide angle light to provide a peripheralillumination. More specifically, light rays following the center beamoptical path, after being emitted by the LED 164, are refracted by thetoroid optic 158, as illustrated at 184 in FIG. 14. These light rays arethen reflected by the mirrored interior surface (154 in FIGS. 13, 19 and20) of the reflector 152 and transmitted through the flat window portion176 and front window 180 of the broadening lens, as illustrated at 186in FIG. 14.

Light rays that follow the wide angle light path, after being emittedfrom the LED 164, are partially collimated by the central bore of thetoroid optic 158 so as to allow ˜30% of the LED light to exit throughthe distal opening of the toroid optic to be used for broad-angleillumination. After the light rays exit the distal opening of the toroidoptic, they are refracted by the dome lens (182 in FIGS. 13 and 17-18B)of the broadening lens and are transmitted through the front window 180of the broadening lens, as illustrated at 192 in FIG. 14.

As a result of the light paths illustrated in FIG. 14 and describedabove, the angles of illumination coverage illustrated in FIG. 21 may beprovided. It is to be understood that FIG. 21 shows a view angle that isthe minimum for most applications. The view angle will vary byapplication

A lens assembly in a cap lamp embodiment of the invention is indicatedin general at 202 in FIGS. 24 and 25. The lens assembly includes abroadening lens 204, having a rim 206, which is positioned within aseparate bezel 208. The bezel features a number of inwardly facingarcuate cutouts 210 which receive corresponding arc-shaped protrusionsformed on the rim 206 of the lens. As a result, the lens does not rotatewith respect to the bezel. The broadening lens features a central optic212.

As illustrated in FIG. 25, the central optic 212 of the lens features acylindrical surface 214 and a parabolic surface 216 surrounded by anannular truncated conical surface 218. As an example only, thecylindrical surface 214 may be defined by the following equation:

$z = \frac{{cx}^{2}}{1 + \sqrt{1 - {\left( {1 + k} \right)c^{2}x^{2}}}}$

Where x is a vertical axis perpendicular to, or coming out of, FIG. 25and z is a horizontal axis running perpendicular to x. The point oforigin is at the bottom or leftmost point of the parabolic surface 216.As an example only, c=−0.25 and k=−1.0.

The parabolic surface 216 may, for example, be defined by the followingequation:

$z = \frac{{cr}^{2}}{1 + \sqrt{1 - {\left( {1 + k} \right)c^{2}r^{2}}}}$

Where x is a vertical axis perpendicular to, or coming out of, FIG. 25and z is a horizontal axis running perpendicular to x. The point oforigin is at the bottom or leftmost point of the parabolic surface 216.As an example only, c=−0.25 and k=−1.0.

As an example only, the lens may be made of Bayer Makrolon 2405 or anyother clear material.

A reflector is indicated in general at 220 in FIGS. 26 and 27. Thereflector has a truncated conical body with rim 224, an internal mirrorsurface 226, or other internal reflective surface, and an enlargedcentral opening 222 (also shown in FIG. 29).

A toroidal or doughnut-shaped toroid optic is indicated in general at230 in FIG. 28 and is preferably formed of a material such as clearpolycarbonate or acrylic. Alternative clear materials may be used. Thetoroid optic includes a truncated cone-shaped central bore 232 with sidewalls 234 that taper outward from a proximal end towards a distal end.The toroid optic features a curved outer surface 236.

As illustrated in FIG. 29, the reflector 220 and toroidal optic 230 areassembled to a circuit board 240 upon which an LED light source 242 ismounted. As an example only, and as illustrated in FIG. 29, each of thetoroid optic and the reflector have feet or posts that engagecorresponding openings in the circuit board 240. When assembled, asillustrated at 220 in FIG. 30, the LED light source is positioned withinthe bore 232 of the toroid optic and the toroid optic is positionedwithin the central opening 222 of the reflector.

With reference to FIG. 30, the assembled components of FIG. 29 arepositioned within the housing of a cordless cap lamp 244. The housingcontains the cap lamp battery, switch, circuit board (240 of FIG. 29)and other components known in the art for such devices. An O-ring gasket246 is sandwiched between the rim of the reflector 220 and the bezel ofthe lens assembly 202, and the assembly is held together by rivets 248.Of course other fastening arrangements may be used.

In view of the above, the present invention provides optic systems toenhance peripheral light or illumination with little to no loss incentral light or illumination.

While the preferred embodiments of the invention have been shown anddescribed, it will be apparent to those skilled in the art that changesand modifications may be made therein without departing from the spiritof the invention, the scope of which is defined by the following claims.

What is claimed is:
 1. A light assembly comprising: a. a light source;b. a reflector having a reflective interior surface and a centralopening within which the light source is positioned; c. a light pipehaving a proximal end and a distal end, said proximal end positionedadjacent to said light source; d. said light pipe adapted so that afirst group of light rays produced by the light source are reflectedwithin the light pipe and directed out of the distal end of the lightpipe at angles to provide peripheral illumination; and e. wherein asecond group of light rays produced by the light source reflect off ofthe reflective interior surface of the reflector to provide centralillumination.
 2. The light assembly of claim 1 wherein the light sourcein a light emitting diode.
 3. The light assembly of claim 1 wherein thelight pipe is formed from clear material.
 4. The light assembly of claim3 wherein the light pipe is formed from clear acrylic or clearpolycarbonate.
 5. The light assembly of claim 1 further comprising alens attached to the reflector with the distal end of the light pipeattached thereto.
 6. The light assembly of claim 5 wherein the lightpipe and lens are integrally formed.
 7. The light assembly of claim 1wherein the proximal end of the light pipe includes an axicon formedtherein.
 8. The light assembly of claim 1 wherein the proximal end ofthe light pipe is textured.
 9. The light assembly of claim 1 wherein theproximal end of the light pipe is provided with a convex lens surface.10. The light assembly of claim 9 wherein the distal end of the lightpipe is textured.
 11. The light assembly of claim 1 wherein the lightsource includes a circuit board and the proximal end of the light pipeis positioned adjacent to the circuit board.
 12. A flashlightcomprising: a. a tube-shaped body; b. a light assembly positioned withinthe body including: i) a light source; ii) a reflector having areflective interior surface and a central opening within which the lightsource is positioned; iii) a light pipe having a proximal end and adistal end, said proximal end positioned adjacent to said light source;iv) said light pipe adapted so that a first group of light rays producedby the light source are reflected within the light pipe and directed outof the distal end of the light pipe at angles to provide peripheralillumination; and v) wherein a second group of light rays produced bythe light source reflect off of the reflective interior surface of thereflector to provide central illumination; c. a battery cell or packpositioned within the body; d. a switching assembly positioned withinthe body and connected to the battery cell and the light source, saidswitching assembly selectively permitting power from the battery cell orpack to flow to the light source.
 13. The flashlight of claim 12 whereinthe light source in a light emitting diode.
 14. The flashlight of claim12 wherein the light pipe is formed from clear material.
 15. Theflashlight of claim 14 wherein the light pipe is formed from clearacrylic or clear polycarbonate.
 16. The flashlight of claim 12 furthercomprising a lens attached to the reflector with the distal end of thelight pipe attached thereto.
 17. The flashlight of claim 16 wherein thelight pipe and lens are integrally formed.
 18. The flashlight of claim12 further comprising a lens attached to the reflector and wherein saidlight pipe is mounted within the body independent of the lens.
 19. Theflashlight of claim 12 wherein the light pipe is mounted within the bodyby a mounting bracket, plate or disk or a formation molded into thebody.
 20. The light assembly of claim 12 wherein the proximal end of thelight pipe includes an axicon formed therein.
 21. The light assembly ofclaim 12 wherein the proximal end of the light pipe is textured.
 22. Thelight assembly of claim 12 wherein the proximal end of the light pipe isprovided with a convex lens surface.
 23. The light assembly of claim 22wherein the distal end of the light pipe is textured.
 24. A lightassembly comprising: a. a light source; b. a reflector having areflective interior surface and a central opening; c. a toroidal-shapedtoroid optic including a central bore, said light source positioned inthe central bore and said toroid optic positioned with the centralopening of the reflector; d. a broadening lens attached to the reflectorand positioned adjacent to said toroid optic, said broadening lensincluding an annular flat window portion, a near beam center-fill lens,a dome lens and a front window; e. said light source producing a firstgroup of light rays that are refracted by the toroid optic, reflected bythe reflective interior surface of the reflector and transmitted throughthe flat window portion and front window of the broadening lens toprovide central illumination; f. said light source producing a secondgroup of light rays that are collimated by the central bore of thetoroid optic, refracted by the dome lens of the broadening lens andtransmitted through the front window of the broadening lens to provideperipheral illumination.
 25. The light assembly of claim 24 wherein thelight source is a light emitting diode.
 26. The light assembly of claim24 wherein the annular flat window portion, near beam center-fill lens,dome lens and front window of the broadening lens are formed as a singlecomponent.
 27. The light assembly of claim 24 wherein the central boreof the toroid optic has a truncated cone shape and the toroid optic hasa generally triangular cross section where an outer surface of thetoroid optic is curved.
 28. A flashlight comprising: a. a tube-shapedbody; b. a light assembly positioned within the body including: i) alight source; ii) a reflector having a reflective interior surface and acentral opening; iii) a toroidal-shaped toroid optic including a centralbore, said light source positioned in the central bore and said toroidoptic positioned with the central opening of the reflector; iv) abroadening lens attached to the reflector and positioned adjacent tosaid toroid optic, said broadening lens including an annular flat windowportion, a near beam center-fill lens, a dome lens and a front window;v) said light source producing a first group of light rays that arerefracted by the toroid optic, reflected by the reflective interiorsurface of the reflector and transmitted through the flat window portionand front window of the broadening lens to provide central illumination;vi) said light source producing a second group of light rays that arecollimated by the central bore of the toroid optic, refracted by thedome lens of the broadening lens and transmitted through the frontwindow of the broadening lens to provide peripheral illumination; c. abattery cell or pack positioned within the body; d. a switching assemblypositioned within the body and connected to the battery cell and thelight source, said switching assembly selectively permitting power fromthe battery cell or pack to flow to the light source.
 29. The flashlightof claim 28 wherein the light source is a light emitting diode.
 30. Theflashlight of claim 28 wherein the annular flat window portion, nearbeam center-fill lens, dome lens and front window of the broadening lensare formed as a single component.
 31. The flashlight of claim 28 whereinthe central bore of the toroid optic has a truncated cone shape and thetoroid optic has a generally triangular cross section where an outersurface of the toroid optic is curved.